DHUM in heat mode / Variable Speed Fan Control

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Joined: Fri Nov 30, 2018 1:24 am

DHUM in heat mode / Variable Speed Fan Control

Post by TheSavageBeagle » Fri Nov 30, 2018 1:33 am

Hello, I'm wondering if it's possible to control a variable speed fan on a WaterFurnace 5 series without their communicating Intellizone2 system, perhaps using a EWC zone board. It might seem like a crazy question, but WF technical support told me that fan speed is tied to compressor staging (low speed and high speed for 1st and 2nd stage respectively. Given this, I saw no reason to go with their communicating system as my ecobees can stage perfectly fine. Since installing the system however, I have learned that there are in fact two fan speeds for 1st stage, and 2 fan speeds for 2nd stage, based on zone calling, when using the Intellizone2. Now I'm kind of frustrated I did not get it, and frustrated they sold me a variable speed fan in the first place.

So anyway, I have verified that the DS/BK terminal on my Honeywell HZ322 zone board will slow fan speed 15% when the system is running and 1 zone is calling, in COOLING mode only. I'm on a wild goose chase to find a board that will allow me to do that in heating mode as well. I realize it may not be possible, as the logic on my WF control board may be looking for my reversing valve to be energized for it to care about the signal at the DHUM terminal. Slowing my fan speed 15% would keep my EAT well below limits, so I am not concerned about it.

Thanks in advance!

Paul Z.
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Joined: Thu Dec 08, 2011 3:05 pm

Re: DHUM in heat mode / Variable Speed Fan Control

Post by Paul Z. » Fri Nov 30, 2018 7:53 am

Call 18004463110X490 have a few questions,

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